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Panhead headache need some advice

7K views 54 replies 10 participants last post by  Lester 
#1 ·
First off
1950 panhead
Super e
Stick points

So about a week ago my bike started running rough, tough starts, cutting out at full throttle carbon fouling rear plug, at idle front cylinder sounded great but rear was off beat like it was missing every other, when you would place yer hand behind rear pipe it did not feel like it was fully firing as the air was almost cool, but when you got on the throttle the air from rear would become hot and felt normal, pulled head and valves look good, inside cylinders look good so did new points,condenser , coil, readjusted push rods and timing, and after all that still no change anybody got any advice ? Thanks
 
#4 ·
what shape is your Super E in? I've had all kinds of annoying problems with my Pan running a Super E.
Did you do new plugs too?

Lester
 
#5 ·
how did you check the valves to the seats - did you fill the head upside down with mineral spirits and see if it leaked by the valves ?????
 
#6 ·
Super e seems to be in pretty good shape seemed to be fine last month I rebuilt it last winter. I have a super b I could throw on and see if it changes anything

I put the head upside down and filled with gas, I was told filling with gas will also work to tell if they are sealing and nothin leaked through but does it have to be the mineral?
 
#7 ·
Gass is fine just more of a fire hazard really.
Yea let us know how the Super B works out... easy swap
Good to eliminate potential problems and moving on.

Lester
 
#9 ·
New plugs? Wires?

Lets run through the basics here.

You say its carbon fouling the rear plug? Wont idle right and picks up at a rev but will cut out a WOT.

At idle, will it suck a dollar bill into the pipe?
Yes new plugs, no extra plug wires but tried a stock style coil with stock style wires, and same outcome,

Yes!! Definitely feels like it could suck one in what causes that? Didn't even think about thar
 
#11 · (Edited)
Definitely as basics go, check voltage. Gordo is "spot on" with that.

As far as sucking in through the exhaust goes, well its usuallly caused by the exhust valve open during the intake stroke. Think about that for a moment. The chamber only holds so much volume. Ideally it should be combustable gas/air mix, not inert exhaust or just air.
 
#12 · (Edited)
You said the valves are sealing, so it has to do with adjustment then. Either pushrod miss adjustment or failure if some kind. Valve spring, lifter, pushrod...etc.

Walk us through your valve adjustment procedure.

Also, what pipes? I am assuming some sort of drag pipe or individual pipes, not combined.
 
#14 ·
You said the valves are sealing, so it has to do with adjustment then. Either pushrod miss adjustment or failure if some kind. Valve spring, lifter, pushrod...etc.

Walk us through your valve adjustment procedure.

Also, what pipes? I am assuming some sort of drag pipe or individual pipes, not combined.
Ok that is all making sense.
I have short drags(I know not very good?with some short mufflwrs

Well I collapse the covers and if I'm adjusting rear exhaust valve I watch for lifter to fully drop down and watch for the front cylinder intake to start coming up to open and then adjust the rear
 
#13 ·
Im thinking this.... Exhaust valve open slightly due to adjustment. Leaning the cylinder out until you throttle it some. The accelerator pump squirts and richens the mix allowing the rear to fire. Pulling fuel through the intermediate circuit until WOT or more than half anyway. Accel pump squirts while rolling on the throttle a bit more keeping the cylinder firing but there is not enough signal to pull from the main jet enough for both cylinders.

The carbon is oil from the cylinder as is normal for cylinder lubrication. As it isnt firing the oil is getting on the plug, once fired it burns.

It makes sense in my head. I hope I completed my sentences and got my thought across.
 
#20 ·
So different carb- nothing
Loosens pushrods- nothing
Another new condensor- nothing
Charging is good

The one thing I did notice was it would idle good when distributer was retarded more than it should be but I tried riding just to see and there was no power, is there anything inside the distributer that could be fucked up wsorn out that could cause this?
 
#24 ·
Dam!
Is the wire going to the circuit breaker in good shape?
Anything shorting on the coil wiring terminals?
Bypass the electrical system with alligator clips/makeshift wiring and see what happens... again just to rule things out.
 
#27 ·
Don't assume because I said do it at full lift that the rear lifter will be on the base. That is the goal, to adjust lash when the lifter is on the base of the cam not on the lobe at all. Depending on cam profile the position of the opposite cylinders lifter may differ.

Its a rule of thumb for a starting point. Still the proper position is what it is for each lifter. To know for sure, use a dial indicator on the lifter you are adjusting.
 
#28 ·
I'd take a good look at the "timing". I was going through some issues with my 54 pan and a lil tweak hear and there can be the difference in 4 kicks or 40. Get shit running and tweak accordingly. My pan had its own sweet spot and went from coughing and sputtering and running like your bike to giving me 230miles of joy today. Just a thought.
 
#30 ·
Any updates?
May be a long shot but I was thinking about Your Circuit breaker gear. Cann't pull it out with out pulling the front head OR if someone has snapped off the bottom cooling fin.

Lester
 
#31 ·
Any updates?
May be a long shot but I was thinking about Your Circuit breaker gear. Cann't pull it out with out pulling the front head OR if someone has snapped off the bottom cooling fin.

Lester
Nope nothing really, just been goin back and re checking everything I have gotten it to run pretty good but as soon as that happens when I turn it off I can't get it to start again.

What about the gear? What do you think could be the issue?
 
#33 ·
As mentioned... the gear may be a far shot BUT if your gear is damaged your timing my be off.

Yup... Leak at the intake manifold may give you loads of problems. you've swaped carbs but have you checked the intake Manifold? If you get it running again you could spray some start sprat in that area... if the revs pick up..... you got a leak. No need to over do it with the spray, several small squirts should do it. keep in mind the fire hazard.

Lester
 
#35 ·
As mentioned... the gear may be a far shot BUT if your gear is damaged your timing my be off.

Yup... Leak at the intake manifold may give you loads of problems. you've swaped carbs but have you checked the intake Manifold? If you get it running again you could spray some start sprat in that area... if the revs pick up..... you got a leak. No need to over do it with the spray, several small squirts should do it. keep in mind the fire hazard.

Lester
Yea I did the spray to check for big leaks and all good there but not able to check for small leaks at this time, once again re adjusted push rods and re did timing,

but tomo gonna go get another set of plugs any of you guys got a good recommendation on some plugs? maybe I'll try something different
And gonna try to again with timing and all that
 
#34 ·
Been down this exact same road before.

For what it's worth... All wires and connections clean? New Properly gapped plugs, I welded a washer in the end of the drag pipes to create a bit of back pressure. (This was my fix), check pushrod adjustment, INTAKE LEAK (I used a air gun and a carb plug), and finally battery voltage.

Good luck hombre

Had it running great 2 months later it won't start.:mad:
 
#36 ·
Been down this exact same road before.

For what it's worth... All wires and connections clean? New Properly gapped plugs, I welded a washer in the end of the drag pipes to create a bit of back pressure. (This was my fix), check pushrod adjustment, INTAKE LEAK (I used a air gun and a carb plug), and finally battery voltage.

Good luck hombre

Had it running great 2 months later it won't start.
Yea redid most of the wiring the other night just to be sure, gonna get another set of new plugs tomo. I feel that my exhaust should be fine, short drags with short mufflers as this is the set up I have always had and checked everything else you have said except compressor is broken so was only able to test manifold for big leaks with spray
 
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